This invention relates generally to motor vehicle clutches, and more specifically, to clutches employing a release sleeve disposed between a device for displacing a release bearing and a clutch spring and/or clutch lever.
Clutches designed for use in heavy and medium duty applications commonly employ a sleeve that is disposed on a transmission driven shaft. The sleeve connects a device for displacing release bearings, commonly known as a release lever, with a clutch spring and/or clutch levers which provide the clutch engagement load against the pressure plate. The sleeve is disposed over the transmission driven shaft and rotates with the spring, as well as the cover, flywheel and pressure plate of the clutch. A bushing in axial alignment with the bearing is press fit in the sleeve for unitary rotation therewith and rides directly on the transmission driven shaft. Relative rotation between the sleeve and the transmission driven shaft occurs when the clutch is partially or fully released. An inner race of the release bearing is connected to the sleeve for movement therewith. The release bearing has an outer race which is prevented from rotating with respect to the inner race and is engaged with a release lever. The release lever has arms which engage wear pads located on an outer axial surface of a bearing housing. The release lever is pivotally mounted in the clutch housing connecting an engine block and a transmission case. The clutch fork is connected with a clutch pedal by a clutch control system for selective axial displacement of the bearing and sleeve and the resulting disengagement of the clutch by the operator. A clutch brake may be provided on the transmission driven shaft between the bearing housing and the transmission case to stop the rotation of the driven shaft. The clutch brake is engaged when the clutch is fully disengaged by the operator.
Release bearing size is determined by the transmission design. Transmission driven shaft diameter varies among transmission models. Some transmissions include a bearing cap extension, or quill, which the release bearing inner diameter must clear. Therefore, a number of bearing sizes need to be provided to accommodate various transmission designs. Bearing size will also impact the clutch design.
Release bearing life is susceptible to debris in the form of friction material from the driven disc facings and environmental contaminants such as dirt, salt and water. These contaminants can be detrimental to the life of the bearing. Heat from the clutch brake may also result in shortened bearing life. Many clutch designs do not have a serviceable bearing, therefore a bearing failure would require clutch replacement.
A clutch assembly is typically supplied with the release bearing assembly installed. When a clutch is manufactured, one of a plurality of release bearing assemblies may be installed in one clutch assembly, which further complicates the assembly process.
Therefore, it is desirous to provide a release mechanism which can accommodate a variety of transmission designs with a single bearing. It is also desirous to provide a release mechanism which protects the bearing seals from contaminants as well as locating the bearing away from the clutch brake. It is further desirous to provide a clutch release mechanism that facilitates bearing replacement when the bearing is worn or damaged. It is still further desirous to provide a clutch release mechanism that simplifies the clutch manufacturing and assembly process by requiring a minimum number of bearing assemblies to be provided with multiple transmission designs.
A release mechanism for a clutch includes a release sleeve slideably disposed on a driven shaft, the release sleeve has an axis of rotation, a first end and a second end. A lever engagement portion is disposed at the first end of the release sleeve for contact with a release lever. A bearing is disposed about the axis of rotation and has an inner race and outer race. A bearing housing portion is disposed at the second end of the release sleeve for receiving the bearing. The bearing housing portion has a shoulder for locating the bearing therein. A retainer is disposed at the bearing housing portion for securing the bearing within the bearing housing by limiting the axial travel of the bearing relative to the release sleeve when the outer race of the bearing is disposed between the shoulder of the bearing housing and the retainer. In one embodiment, the release mechanism includes a bearing sleeve which has a bearing mount portion for locating a bearing thereon and a spring portion for receiving a radially inward portion of a biasing spring or a lever. Alternatively, the inner race of the bearing may include a spring support portion for receiving a radially inwardly portion of a biasing spring or lever, disposing of the bearing sleeve all together. Furthermore, a bushing is disposed within an inner radial surface of the release sleeve. A clutch brake may be provided which extends about the driven shaft and disposed adjacent to the contact surface of the release sleeve and axially spaced from the bearing housing portion.
In an alternate embodiment, the release mechanism includes a selectively engageable retainer disposed at the bearing housing portion. The retainer is moveable from a first radial position to a second radial position relative to the axis of rotation. In one embodiment, the selectively engageable retainer comprises at least one radially extending detent portion which is moveable from a first radial position to a second radial position relative to the axis of rotation. A biasing member cooperates with the detent for urging the detent toward one of a first or second radial position. A cam cooperates with the detent where the cam is rotatable from a first angular position to a second angular position relative to the release sleeve. A radially extending lever cooperates with the cam to cause the cam to rotate from a first angular position where the detent is at a first radial position, to a second angular position where the detent is moved to a second radial position.
A clutch includes a driving member having an axis of rotation, a cover coupled to the driving member for rotation therewith and a pressure plate coupled to the cover for rotation therewith. A driven member is coupled to an axially extending driven shaft for rotation therewith. The driven member is interposed between the driving member and the pressure plate. A biasing member is disposed between the pressure plate and the cover to bias the pressure plate toward the driven member. A release sleeve is slideably disposed on a driven shaft, the release sleeve rotates on the axis of rotation and has a first end and a second end. A lever engagement portion is disposed at the first end of the release sleeve for contact with the release lever. A bearing is disposed about the axis of rotation and had an inner race and outer race. A bearing housing portion is disposed at the second end of the release sleeve for receiving the bearing. The bearing housing portion has a shoulder for locating a bearing therein. A retainer is disposed at the bearing housing portion for securing the bearing within a bearing housing by limiting the axial travel of the bearing relative to the release sleeve when the outer race of the bearing is disposed between the shoulder of the bearing housing portion and the retainer.
Other objects and features of the invention will become apparent to those skilled in the art as disclosure is made in the following detailed description of a preferred embodiment of the invention which sets forth the best mode of the invention contemplated by the inventors and which is illustrated in the accompanying sheets of drawings and the appended claims.